GB1512649A - System providing information relating to depth and movement in a fluid - Google Patents

Abstract

1512649 Measuring system KINETRONICS INDUSTRIES Inc 29 Sept 1975 [27 Sept 1974] 39856/75 Heading GIN A system for providing information relating to depth or height and movement in a fluid comprises depth or height responsive means 1 connected to an electrical power source for generating electrical signals V 1 reflective of instantaneous depth or height, means for measuring the values of the electrical signals V 1 at predetermined intervals so as to generate, in use, electrical signals V 5 representative of the actual rate of change of depth or height of the system over the intervals and means for generating a reference signal V REF representative of a predetermined rate of change of depth or height. The actual rate of change signal is compared, in use, with the predetermined rate of change signal in a comparator 13, an electrical warning signal being generated when the actual rate exceeds the predetermined rate. The described embodiment is directed towards providing said information to a scuba diver and the depth responsive means comprises a transducer 1 in the form of a bridge strain gauge Fig. 5 (not shown) which generates analog voltage signals V 1 reflective of the ambient pressure and thus depth of the system. A first amplifier 3 amplifies the signals V 1 from the transducer 1, the signals V 2 being produced thereby passing to a pair of sample and hold devices 5, 7. The sample and hold devices 5, 7 form part of the aforesaid measuring means. A timing oscillator provides a train of pulses Fig. 9 (not shown) from which are produced in each cycle a pair of timing pulses to provide said predetermined intervals. Each of a pair of timing pulses, SIG.A, SIG.B is fed to a different one of the sample and hold devices 5, 7 such that the outputs V 3 , V 4 thereof comprise depth measurements at successive times. These outputs V 3 , V 4 are fed to a differential amplifier 11 for comparison and the output V 5 then being, as stated above, fed to a comparator. From the sign of the output V 5 an indication is given as to whether the diver is ascending or descending in the water, the means for effecting such comprising ascent and descent comparators 17, 19 and associated indicators 21, 23. The system also provides a temperature measurement transducer 31 and a time of dive measurement. The latter is provided by counting the number of pulses generated by the oscillator. The three measurements are selectively displayable on a digital read-out, Fig. 4 (not shown) but since the depth and temperature measurements are analog an analogue to digital converter is provided Also a data select circuit and switching means are provided for selecting the data required to be displayed. A pressure operated switch arrangement is provided, Fig. 10 (not shown) for activating the system only when necessary. A delay in switching off the system is built into the switch arrangement.